Ferguson also admits that van Persie was desperate to leave Arsenal and join United.

The Dutchman moved to Old Trafford in August last year in a decision that left Arsenal fans fuming and the Manchester United boss delighted.

Van Persie scored 26 goals in his first league season as Manchester United romped to a 13th Premier League title under Ferguson.

And writing in his new book - My Autobiography - Ferguson said it was the striker himself who was keen to have talks with the club.

After finding out about Van Persie's interest, the then Manchester United boss spoke on the phone to Arsenal boss Arsene Wenger several times to seal the move.

Ferguson wrote: "I warned Arsene we would never get to £25m. Arsene was incredulous. He could not believe that Manchester United wouldn't stretch to £25m for such a player.

"I told him again: I wouldn't go to £25m. Arsene asked what my best offer would be. Answer: £22m. The reply was that Arsenal would take £22.5m and a further £1.5m if we won the Champions League or Premier Leaguer during the period of his contract. Deal done."

Arsene Wenger said the transfer had gone through: "It was a very professional phone call (from Ferguson) and there was more than one. I will tell you the rest another day."

Earlier this summer, Van Persie revealed his side of the story and confirmed it was his wish to move to Old Trafford.

He told MUTV in June : “...it wasn’t only me who decided where I went to play. I also depended on my former club as well and how they saw it.

“And then of course you always have these games that the directors play.

(Image: Paul Thomas)

“It’s a bit like a rollercoaster. Some days it is looking good and other days it is worse. You don’t really know what to expect because things can change so quickly.

“It normally depends on the player and the two teams, but in my case, there were two other teams involved as well.

“One was [Manchester] City and the other one was Juventus. So it was a bit hectic but I always wanted this transfer from day one."

Van Persie scored his first goal in the 3-2 win over Fulham on August 25, before scoring a hat-trick against Southampton a week later.

And he finished as the league's top goalscorer, three ahead of Luis Suarez, to help United to an 11-point triumph and their 20th league title.

To order your copy of Alex Ferguson: My Autobiography (Hodder & Stoughton) (RRP £25) at the special offer price of £19.99 with free P&P, please call the Mirror Bookshop on 0871 803 6772.